Want to upgrade your 2009 or later iMac’s hard drive or memory? There’s a very good chance that it can be done, depending on the model you own. But before you dive in on your upgrade – and even if you already have begun – there are some very important things you need to know.

The Rocket Yard has outlined a guide on some of the most crucial information you’ll need when it comes to upgrading your iMac.

1) Avoid the Noise
If you have previously researched a guide on how to upgrade the hard drive in your iMac, you might have come across fellow iMac owners commenting on issues involving a blaring, revving or noisy fan.

If you haven’t, we will break it down for you:

The problem: With the introduction of the iMac, Apple’s factory-installed drives contained custom firmware that communicated thermal data to the System Management Controller (SMC). Unfortunately, off-the-shelf hard drives don’t include the custom firmware, and as a result, the SMC is unable to monitor the temperature of the hard drive. This causes the iMac fans to run at full speed and fail Apple diagnostics as a failsafe. Despite various “hacks”, the best solution was to still use Apple’s SMC to ensure proper monitoring of drive and system health.

The solution: Fortunately, OWC was able to come up with a solution with its In-Line Digital Thermal Sensor – the first hardware digital thermal sensor on the market allowing a third-party SATA drive to be installed in an iMac. The sensor eliminates “blaring” fan noise and maintains proper system fan control through the iMac’s System Management Controller. The sensor is designed specifically for the iMac, requires no software hacks, and ensures compatibility with Apple’s built-in diagnostic processes.

So, if you’ve upgraded your iMac’s hard drive and notice a blaring fan, don’t panic. There is a solution. For more on this topic, please read this Rocket Yard article.

2) Maximum Internal Capacity
It might not seem so on the surface, but the all-in-one iMac can fit more storage internally than you might have thought*. In fact, some iMac models have more than one drive bay and can even swap out the optical drive for Data Doubler. With our My Upgrades tool, you can see how much storage each iMac model from 2009-current is compatible with.

3) Professional Installation Recommended
While the sleek design makes late 2012-current iMac models aesthetically pleasing, it also brings challenges when upgrading internal hardware. If you are planning an upgrade for one of these iMacs, it is highly recommended that you seek professional installation. After all, an iMac is much less aesthetically pleasing with a crack on its screen.

4) Adding More MemoryEvery iMac – aside from some of the latest 21.5” models – is compatible with a memory upgrade. In fact, the 27-inch Late 2015 iMac with Retina 5K display is compatible with up to 64GB of RAM!

Visit our convenient My Upgrades tool to see how much memory your iMac is compatible with.

5) Newly Vintage, But Sierra Compatible
Apple considers iMacs models from before 2009 “obsolete”. The models from 2009 are considered “vintage” as of March 2016. But what does this mean? Here is Apple’s definition of the terms.

Vintage: Products that have not been manufactured for more than five and less than seven years ago. Apple has discontinued hardware service for vintage products with a few exceptions that can be found here.

Obsolete: Products that were discontinued more than seven years ago. Apple has discontinued all hardware service for obsolete products with no exceptions. Service providers cannot order parts for obsolete products.

Of course, in the world of Macs, obsolete doesn’t have to mean obsolete. And as for the Late 2009 iMac, it might be considered vintage, but it is still compatible with macOS Sierra so you will have access to the latest Mac operating system.

Upgrades Made Easy
Upgrading the hard drive or memory in your iMac is a great way to boost its performance and extend its lifespan. To see all of the upgrade options for your iMac, check out the MacSales.com My Upgrades search tool to find your specific model and compatible upgrade solutions!

Hello, I have a late 2009 21.5in iMac. I upgraded to High Sierra some time ago and I noticed that my built-in CD drive no longer recognizes that a disc in present and will not play. Is this due to my High Sierra upgrade or something else? And is there anything I can do? Thanks!

Thank you so much for asking about your machine. The late 2009 iMac is currently only compatible up to macOS High Sierra. At this time there is no option to upgrade further to macOS Mojave or Catalina.

No. I upgraded to ssd and more ram but my video card and cpu need upgrading too. I have a mid iMac 2011 running high Sierra. Runs fantastic but I can’t upgrade the iOS until I upgrade more hardware.
I have an amd video card and metal doesn’t support them.

I have a iMac 27” i5 mid 2010 model, my optical drive doesn’t work and the HD crashed all else on computer is good and it still looks new.
Question should I install new Samsung 850 SSD and add 8 megs of Ram more to the std 4 that came with it and hope my computer can run as efficiently as the ones out now. I know an SSD drive is better than the Fusion drive they now have aren’t they? The optical dive I don’t need so I will just let it be. Should I do this to an old 10yr old iMac or get a new iMac. Will it last a long time or will it do no good and waste of time with it’s current operating system even with the SSD and ram mentioned.
HELP…..

Installing an SSD and increasing the amount of RAM you have will improve the performance substantially! Check out all the upgrade options for your iMac at MacSales.com, you’ll find every SSD and RAM option available for your model as well as install videos for everything.

Also, if you don’t plan on using the optical drive any longer, you can swap that out for another SSD. It’s called Data Doubler, and you can check it out here.

Thanks so much for the reply! I’ve been poking around all over and found a lot of conflicting advice. Can you fill me in on why the 2 x 4GB RAM should be moved to the upper slots (BANK 0 DIMM 0, and BANK 1 DIMM 0, right)?
Thanks again!

Hello! I want to update the memory in my dual core late 2009 iMac from 4GB to 12GB. Currently, I have 2 x 2GB RAM that live in the two top slots. If I purchase 2 x 4GB RAM, should I install in the bottom two slots, or should each size pair live in its own bank together (one on top, one on bottom)?
Thanks!

Thanks so much for the reply! I’ve been poking around all over and found a lot of conflicting advice. Can you fill me in on why the 2 x 4GB RAM should be moved to the upper slots (BANK 0 DIMM 0, and BANK 1 DIMM 0, right)?
Thanks again!

Someone just gave me their old iMac 21.5″ late 2009 desktop computer. I’ve wiped it and recently installed the latest operating sys. macOS Sierra version 10.12.6, but now it barely runs. My question is- is it worth it to upgrade the memory or just better off getting rid of the thing? It currently has only 4GB installed.

Hi Jarrod
Thanks for your speedy response! For the “drastic” performance boost” would I have to do both memory and SSD or just the SSD? And if I just did the 16GB of memory would that be satisfactory for just internetting and light photo editing?

I have a 2010 27″ Mac that I replaced with a 2015 model when the hard drive died (Apple Store Tech diagnosis). I don’t have a pressing need for it; but, is there any reason to try to bring it back to life (with your expert help)?

Hi, Martin. A 2010 iMac can still be a great machine with the right upgrades. Please feel free to contact our customer support team, which will be more than happy to go over your options. As for reasons to bring it back to life, it can make a perfect hand-me-down or backup machine.

I had a 2009 27″ iMac that stopped booting when I was in the middle of a big project. I had a new iMac delivered the next day and put the 2009 on the shelf for two years. Last fall I took the busted one in to the Apple Store and found the problem was a bad video card, a cheap fix. I then replaced the optical drive with an OWC data doubler 1TB SSD and the 2009 Mac now performs better than my newer Mac. For a few hundred bucks I have a great machine. It was well worth it.

Re: Upgrading to Sierra
I have two mid-2011 iMacs that are running well on El Capitan. Both have max RAM and SSDs added behind the optical drive. It is said that the latest system isn’t always a good idea in an older computer that wasn’t designed to run it. Are these mid-2011s up to running Sierra without becoming sluggish?

Great article, and timely in my case. I just bought from OWC and installed 16 GB RAM and a 1TB SSD with the DIY kit in a 2010 21″ iMac that I picked up used for $400. The OWC DIY kit had everything I needed. Only thing additional was an external USB enclosure for the original 3.5″ drive. The OWC installation videos are great, much better than some of the other teardown/fixit sites that have only step by step pictures. If a picture is worth a thousand words, and a video is worth a thousand pictures, then how many words your videos worth? AWESOME tech support from OWC!

Long time OWC customer, many DIY upgrades going back to G3/G4 days, thought the iMac case would be too tough to crack open after working in those massive desktop and tower cases of yesteryear. Your video shows exactly how easy it is. Now, can you make one to show how to replace the thermal paste on the CPU and video card heat sinks in an iMac? …

Question, I have an early 2009 24″ iMac. I’m thinking it needs a motherboard replacement. I would like to replace with say a board from a 2011. Is that possible? If not how new can I go? I also plan on replacing the 1TB with a SSD drive.

Thank you so much for your question! We are very sorry but we are not able to verify if a 2011 motherboard will be compatible with your early 2009 24″ iMac. We would recommend to contact the manufacturer for any motherboard upgrades or replacements.

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